What does FR mean on an oversize permit?

Frontage road. The frontage road beside a highway, not the main lanes: IH35WFR is the west frontage road of I-35.

Also printed as FRONTAGE, SVC RD.

On real permits

PrintedMeansState
I-285 Frontage Road SWThe frontage road beside I-285, heading southwestGeorgia

Decode a whole route line